Periodontitis during pregnancy: The effect on the gut microbiome and intestinal inflammation

BACKGROUND: Periodontitis has been epidemiologically associated with adverse pregnancy outcomes, but causality remains difficult to establish in humans due to confounding factors. This study uses a controlled murine model to examine the effects of experimentally induced periodontitis on the composition of the gut microbiota and gastrointestinal inflammation during pregnancy. METHODS: Periodontitis was induced in pregnant BALB/c mice via oral inoculation with Porphyromonas gingivalis and Fusobacterium nucleatum before conception (n = 20 per group). Pregnancy outcomes, gut histology, systemic inflammatory markers, and microbiome composition, assessed by 16S rRNA sequencing, were evaluated at gestational Day 18. RESULTS: Periodontitis was confirmed by significant alveolar bone loss. While fetal and placental weights were modestly increased in periodontitis-positive mice, there were no changes in implantation rates or placental efficiency. Systemic inflammatory markers, including C-reactive protein and interleukin-33, were reduced, suggesting pregnancy-specific immunomodulation. Histological analysis revealed significant inflammation in the jejunum and colon of periodontitis-exposed mice. Despite this, alpha and beta diversity metrics of the gut microbiota remained essentially unchanged. Taxonomic shifts were observed at the genus level, with reductions in protective taxa, such as Akkermansia muciniphila and increases in potentially pro-inflammatory genera, like Desulfovibrio. CONCLUSIONS: Periodontitis during pregnancy alters gut microbial composition and increases gastrointestinal inflammation without overtly impairing pregnancy outcomes in mice. These findings suggest an association between oral inflammation, intestinal inflammatory changes, and systemic inflammatory modulation during pregnancy. Further studies are warranted to explore long-term maternal and offspring consequences and their relevance to human pregnancy. PLAIN LANGUAGE SUMMARY: This study explored how periodontitis during pregnancy can influence the gut and immune system. Periodontitis is already associated with poor pregnancy outcomes, but establishing cause and effect in humans is difficult. To investigate this, the researchers used a controlled mouse model. We induced periodontitis in pregnant mice and examined its impact on the gut microbiome, intestinal health, and immune responses. The results revealed that periodontitis does not stay confined to the mouth; it disrupts gut bacterial balance, causes gut inflammation, and modifies immune pathways. Notably, these effects occurred during pregnancy, a time when the immune system is already adapting. The findings suggest that oral infections during pregnancy can have widespread effects, impacting gut health and immune regulation. This may help explain the link between periodontitis and human pregnancy complications. Overall, the study underscores the importance of oral health during pregnancy and supports the idea that treating periodontitis might also safeguard gut and immune health, leading to better outcomes for both mothers and their babies.